In nuclear fuel bundles having part-length fuel rods, it has been proposed to provide swirlers in the fuel bundle in the space above the part-length fuel rods to direct the flow of coolant/moderator into and between the fuel rods laterally adjacent the space. Prior swirler designs typically mount the swirlers on the spacer or spacers above the upper end of the part-length fuel rods. The swirlers are either integrated into the spacer body or are welded to the spacer. In both cases, the spacers are not separate entities after installation and cannot be removed absent disassembly of the bundle. Swirlers fixed to the spacer, for example, by welding, require additional bundle assembly process steps, which are labor-intensive and, hence, increase the costs of the fuel bundle. Moreover, the swirlers cannot be removed from the spacer in the event of a failure of the part-length fuel rod without disassembly of the bundle and shipment of the bundle skeleton to a repair site. While there is thus a demonstrated need for a swirler which can be readily attached and detached relative to the spacer, it is quite counterintuitive to provide a removable swirler in a nuclear fuel bundle. That is, strenuous efforts are made to maintain the structure of the fuel bundle and ancillary reactive parts intact during operation and the concept of having a removable part within the nuclear fuel bundle would be counter to the longstanding desire to avoid unsecured parts in the reactor.